CT – Pulmonary Angiogram

(CTPA)

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Features

-  Special CT test designed to pick up PE

-  IV contrast is used to highlight pulmonary vessels

-  Introduced as alternative to V/Q scans

-  Typically preceded by CXR

 

Procedure

-  IV cannula

-  20G+ preferred

-  Cubital fossa preferred over dorsum of hand

-  Patient supine

-  50-150ml radiocontrast via syringe driver

-  Dr to observe injection of contrast so that dye does not tissue

-  CT Scanning

-  Bolus scanning detects when contrast is at prox pulmonary a. then begins OR

-  Manually started 10-12 sec after injection

-  State of the art scanners complete in +/-5 sec

 

Interpretation

-  Contrast appears white on CT

-  Mass filling defects (ie: emboli) appear darker

 

CTPA Saddle PE

 

Contraindications

-  ARF, CRF: contrast --> worsen

-  May use NAC

-  Known contrast reaction: Anaphalaxis

-  Pregnancy: high dose radiation, unless 3rd trimester then cosider